FGF-1 SECRETION PATHWAY

肝素结合蛋白，成纤维细胞生长因子（FGF）-1，是一种 一个大家族的原型成员的相关基因，它缺乏 引导其通过内质网分泌的结构特征 网状高尔基复合体由于FGF-1是一种有效的血管生成因子， 已经被认为是血管病理生理学的介质， FGF-1的分泌机制可能是一种重要的调节机制， 功能来控制这种蛋白质的生物活性。因此， 此应用程序的长期目标是定义负责 FGF-1分泌。我们之前已经证明，温度导致 FGF-1作为一种蛋白质的分泌，它是生物学上无活性的， 以高亲和力与肝素结合。然而，（NH 4）2S 〇 4和更多 最近，还原剂能够激活肝素结合， 潜在FGF-1的生物活性。事实上，最近的诱变研究 与FGF-1的结合证实了后一种观察，因为无半胱氨酸的FGF-1 突变体不响应温度而分泌。另外我们有 其特征在于FGF-1为磷酸化丝氨酸（pLS）结合蛋白，并具有 暗示了突触结合蛋白（stg）的功能， 参与胞吐运输，作为一个潜在的候选人，调解 FGF-1的分泌。最后，我们获得了初步证据， 氧化型低密度脂蛋白和缺氧能够诱导 FGF-1作为肝素结合生长因子的释放。这些数据支持 我们的近期目标，其中包括（一）定义的作用， FGF-1的半胱氨酸残基及stg在FGF-1中的潜在功能 分泌途径，（ii）鉴定和表征 参与FGF-1分泌途径的细胞内因子， (iii)确定是否有其他生物压力，如缺氧， 和深度缺氧能够利用这种非常规途径， FGF-1分泌。预计这些结果将最终 不仅有助于我们理解FGF-1是如何调节 但是FGF-1分泌途径的定义可能 还对FGF-1分泌的机制产生了新的见解， 可以抑制通路。事实上，最近已经有可能共同- 使用新的电泳方法从培养基中定位FGF-1和stg FGF-1转染的NIH 3 T3细胞在热休克和NIH 3 T3 用FGF-1和反义stg共转染的细胞不能释放FGF-1， 对温度应激的反应。

The heparin-binding protein, fibroblast growth factor (FGF)- 1, is a prototype member of a large family of related genes and it lacks the structural feature to direct its secretion through the endoplasmic reticulum-Golgi complex. Because FGF-1 is a potent angiogenesis factor and has been implicated as a mediator of vascular pathophysiology, the mechanism by which FGF-1 is secreted may be an important regulatory feature to control the biological activity of this protein. Thus the long term goal of this application is to define the mechanism responsible for FGF-1 secretion. We have previously shown that temperature results in the secretion of FGF-1 as a protein which is biologically inactive and fails to associate with heparin with high affinity. However, (NH4)2S04 and more recently reducing agents are able to activate the heparin-binding and biological activity of latent FGF-1. Indeed, recent mutagenesis studies with FGF-1 confirm the latter observation since a cysteine-free FGF-1 mutant is not secreted in response to temperature . In addition, we have characterized FGF-1 as a phosphatydylserine (pLS)binding protein and have implicated the function of synaptotagnin (stg), a pLS-binding protein involved in exocytotic traffic, as a potential candidate for mediating the secretion of FGF-1. Lastly, we have obtained preliminary evidence that oxidized low density lipoprotein and hypoxia are able to induce the release of FGF-1 as a heparin-binding growth factor. These data support our immediate goals and these include (i) the definition of the role of FGF-1 cysteine residues and the potential function of stg in the FGF-1 secretion pathway, (ii) the identification and characterization of intracellular factors that participate in the FGF-1 secretion pathway and (iii) determine whether alternative biological stresses such as hypoxia and profound hypoxia are able to utilize this non-conventional pathway for FGF-1 secretion. It is anticipated that these results will in ultimately contribute not only to our understanding of how FGF-1 is able to regulate angiogenesis in vivo but definition of the FGF-1 secretion pathway may also yield new insight into mechanisms by which the FGF-1 secretion pathway may be inhibited. Indeed, it has recently been possible to co- localize FGF-1 and stg using novel electrophoretic methods from the medium of FGF-1-transfected NIH 3T3 cells conditioned by heat shock and NIH 3T3 cells co-transfected with FGF-1 and antisense stg fail to release FGF-1 in response to temperature stress.